1. Field of the Invention
The present invention relates to an image forming apparatus capable of detecting a communication error and a communication control program product.
2. Description of the Related Art
Image processing of an image forming apparatus is controlled by communication among a plurality of units for performing various controls in the image forming apparatus. In some units, the power may be turned off when the predetermined door provided for the image forming apparatus is opened (hereinafter this trigger may be referred to as “door opening”). In the image forming apparatus provided with such a kind of unit, the normal communication is not initiated between the apparatus and the unit if the door opening occurs.
In order to overcome this inconvenience, there is a known method of detecting the communication error by the parity check, and checking the opening/closing status of the door after the communication error is detected, in order to determine whether the communication error is caused by the door opening or by a trouble of the communication means or lines.
For example, Japanese Patent Application Laid-open No. H04-213271 discloses a configuration provided with a door opening/closing detecting unit for detecting the opening/closing status of the door in order to determine the communication error is caused by the door opening or by the trouble of the communication means or lines (the true communication error), a communication status detecting unit such as parity check for detecting that the communication is normally initiated, a communication monitoring unit for storing the detection result, and a self diagnosing unit for diagnosing the status of the apparatus on the basis of the detecting result of the door opening/closing detecting unit and the content stored in the communication monitoring unit.
However, the disclosed method has a problem as follows. In a case that the door opening occurs in the middle of communication, the parity check may fail in detecting the communication error at some timing between the data transfer and the door opening detection. Therefore, there is a risk that a wrong data is retrieved.